The Bottle Gourd (Lagenaria siceraria) leaves attract aphids (Superfamily: Aphidoidea) that gather on the undersurface to feed on the plant sap (video below).
As these tiny insects suck up the plant sap, excess sap is excreted from the anus as honeydew. The honeydew is sweet and attracts ants that gather around to feed on this liquid. The presence of ants deters predators from the aphid colony (video below). At the same time the pair of tubes (cornicles) sticking out from the back of the aphids also deter predators as they exude defensive chemicals like waxes. As female aphids lay unfertilized eggs, they are very successful as a group
One of the natural enemies of aphids is the ladybird, a beetle, also known as ladybug. The most common ladybird in Singapore is the Transverse Ladybird (Coccinella transversalis) that can grow up to 6mm. It is bright orange to red with black markings across the elytra (Ng et al., 2011). The lifecycle of the ladybird beetle starts with the yellow eggs.
The eggs hatch into larvae.
And the larvae develop into pupae.
Finally, the adult ladybirds emerge from the pupae.
The presence of ladybirds indicates a healthy garden. The adult ladybirds as well as their larvae, being carnivorous, feed on aphids and other plants pests, thus keeping the populations of these pests under control.
YC Wee & Dr Leong Tzi Ming
21st May 2019
Ng, P.K.L., R. Corlett & H.T.W. Tan (eds.) 2011. Singapore Biodiversity: An encyclopedia of the Natural Environment and Sustainable Development. Editions Didier Millet & Raffles Museum of Biodiversity Research, Singapore. p. 356.